Comparative assessment of CacyBP/SIP, ß-catenin and cannabinoid receptors in the adrenals of hypertensive rats.

Taking into account homeostatic disorders resulting from arterial hypertension and the key importance of CacyBP/SIP, ß-catenin and endocannabinoids in the functioning of many organs, it was decided to assess the presence and distribution of CacyBP/SIP, ß-catenin, CB1 and CB2 in the adrenal glands of hypertensive rats of various aetiology. The study was conducted on the adrenal glands of rats with spontaneous and renovascular hypertension. The expression of CacyBP/SIP, ß-catenin, CB1 and CB2 was detected by immunohistochemistry and real-time PCR method. The results of the present study revealed both lower gene expression and immunoreactivity of CacyBP/SIP in the adrenal glands of all hypertensive groups compared to the normotensive rats. This study demonstrated a reduction in the immunoreactivity and expression of the ß-catenin, CB1 and CB2 genes in the adrenals of 2K1C rats. While in SHR, the reaction showing ß-catenin and CB1 was very weak or negative, and the expression of CB2 in the adrenal glands of these rats increased. The results of this study show, for the first time, marked differences in the expression of CacyBP/SIP, ß-catenin and CB1 and CB2 cannabinoid receptors in the adrenal glands of rats with primary (SHR) and secondary hypertension (2K1C).

Endovascular interventions in main renal artery pathologies: an overview and update.

Renal arteries are involved in a wide spectrum of pathologies including atherosclerosis, fibromuscular dysplasia, Takayasu arteritis, aneurysms, and aortic type B dissections extending into main renal arteries. They manifest as renovascular hypertension, renal ischemia, and cardiovascular dysfunction. The location of the renal arteries in relation to the abdominal aortic aneurysm is a critical determinant of interventional options and long-term prognosis. This article provides a comprehensive review of the role of interventional radiologists in transcatheter interventions in various pathologies involving the main renal arteries with analysis of epidemiology, pathophysiology, newer interventional techniques, and management options.

Bone marrow-derived mesenchymal stem cells transplantation ameliorates renal injury through anti-fibrotic and anti-inflammatory effects in chronic experimental renovascular disease.

BACKGROUND: Progressive renal fibrosis is an underlying pathological process of chronic kidney disease (CKD) evolution. This study aimed to evaluate the roles of bone-marrow-derived mesenchymal stem cells (MSC) in the remodeling of fibrotic kidney parenchyma in the two kidneys-one clip (2K1C) CKD animal model. METHODS: Wistar rats were allocated into three groups: Sham, 2K1C, and 2K1C þ MSC. MSCs (106) were transplanted into the renal subcapsular region two weeks after clipping the left renal artery. Six weeks after clipping, left kidney samples were analyzed using histological and western blotting techniques. ANOVA tests were performed and differences between groups were considered statistically significant if p < 0.05. RESULTS: Clipped kidneys of 2K1C rats displayed renal fibrosis, with excessive collagen deposition, glomerulosclerosis and renal basement membrane disruption. Clipped kidneys of 2K1C þ MSC rats showed preserved Bowman's capsule and tubular basement membranes, medullary tubules morphological reconstitution and reduced collagen deposits. Expression levels of matrix metalloproteinase (MMP)-2 and MMP-9 were elevated, whereas tissue inhibitor of MMPs (TIMP)-1 and TIMP-2 levels were decreased in clipped kidneys of 2K1C rats. MSCs transplantation restored these expression levels. Moreover, MSCs suppressed macrophages and myofibroblasts accumulation, as well as TNF-a expression in clipped kidneys of 2K1C animals. MSCs transplantation significantly increased IL-10 expression. CONCLUSIONS: Transplanted MSCs orchestrate anti-fibrotic and anti-inflammatory events, which reverse renal fibrosis and promote renal morphological restoration. This study supports the notion that only one MSCs delivery into the renal subcapsular region represents a possible therapeutic strategy against renal fibrosis for CKD treatment.

Radiation-induced kidney toxicity: molecular and cellular pathogenesis.

Radiation nephropathy (RN) is a kidney injury induced by ionizing radiation. In a clinical setting, ionizing radiation is used in radiotherapy (RT). The use and the intensity of radiation therapy is limited by normal-tissue damage including kidney toxicity. Different thresholds for kidney toxicity exist for different entities of RT. Histopathologic features of RN include vascular, glomerular and tubulointerstitial damage. The different molecular and cellular pathomechanisms involved in RN are not fully understood. Ionizing radiation causes double-stranded breaks in the DNA, followed by cell death including apoptosis and necrosis of renal endothelial, tubular and glomerular cells. Especially in the latent phase of RN oxidative stress and inflammation have been proposed as putative pathomechanisms, but so far no clear evidence was found. Cellular senescence, activation of the renin-angiotensin-aldosterone-system and vascular dysfunction might contribute to RN, but only limited data is available. Several signalling pathways have been identified in animal models of RN and different approaches to mitigate RN have been investigated. Drugs that attenuate cell death and inflammation or reduce oxidative stress and renal fibrosis were tested. Renin-angiotensin-aldosterone-system blockade, anti-apoptotic drugs, statins, and antioxidants have been shown to reduce the severity of RN. These results provide a rationale for the development of new strategies to prevent or reduce radiation-induced kidney toxicity.

Different reactive species modulate the hypotensive effect triggered by angiotensins at CVLM of 2K1C hypertensive rats.

Hypertension is associated with increased central activity of the renin-angiotensin system (RAS) and oxidative stress. Here, we evaluated whether reactive species and neurotransmitters could contribute to the hypotensive effect induced by angiotensin (Ang) II and Ang-(1-7) at the caudal ventrolateral medulla (CVLM) in renovascular hypertensive rats (2K1C). Therefore, we investigated the effect of Ang II, Ang-(1-7), and the Ang-(1-7) antagonist A-779 microinjected before and after CVLM microinjection of the nitric oxide (NO)-synthase inhibitor, (L-NAME), vitamin C (Vit C), bicuculline, or kynurenic acid in 2K1C and SHAM rats. Baseline values of the mean arterial pressure (MAP) in 2K1C rats were higher than in SHAM rats. CVLM microinjection of Ang II, Ang-(1-7), l-NAME, or bicuculline induced decreases in the MAP in SHAM and 2K1C rats. In addition, Vit C and A-779 produced decreases in the MAP only in 2K1C rats. Kynurenic acid increased the MAP in both SHAM and 2K1C rats. Only the Ang-(1-7) effect was increased by l-NAME and reduced by bicuculline in SHAM rats. L-NAME also reduced the A-779 effect in 2K1C rats. Only the Ang II effect was abolished by CVLM Vit C and enhanced by CVLM kynurenic acid in SHAM and 2K1C rats. Overall, the superoxide anion and glutamate participated in the hypotensive effect of Ang II, while NO and GABA participated in the hypotensive effect of Ang-(1-7) in CVLM. The higher hypotensive response of A-779 in the CVLM of 2K1C rats suggests that Ang-(1-7) contributes to renovascular hypertension.

Kidney enlargement effect of angioplasty for nonatherosclerotic renovascular disease: reversibility of ischemic kidney.

Renal artery stenosis causes kidney ischemia, reducing the size of the affected kidney, which eventually results in atrophy. Although renal atrophy is considered irreversible, resolution of the ischemia occasionally restores kidney size when the cause is renal artery stenosis. Angioplasty is effective in patients with nonatherosclerotic renovascular diseases (non-ARVDs). Nevertheless, renal enlargement after angioplasty has not been fully examined. We conducted a retrospective study to examine this phenomenon in non-ARVD patients. Ten patients with a <100-mm pole-to-pole length of the poststenotic kidney were treated with angioplasty. Data were collected up to 12 months after angioplasty. The mean age was 28 years; the estimated glomerular filtration rate was 92 ± 7 mL/min/1.73 m2 (mean ± SEM); blood pressure was 150/99 mmHg; 80% were women; and fibromuscular dysplasia was present in 90% of the patients. All patients had hypertension. The lengths of the poststenotic and contralateral kidney before angioplasty were 91 ± 1 and 111 ± 3 mm, respectively. After angioplasty, the length of the poststenotic kidney gradually increased during the 3 months after treatment (+5.4 mm) and that of the contralateral kidney decreased over the same time course (-3.7 mm). Enlargement was also found in the moderate atrophy subgroup (length < 92 mm), and it was greater in the <30 years old group. In a noteworthy case, renal size in the poststenotic kidney recovered from 87 to 102 mm after angioplasty. Our findings demonstrated that reduced renal size can be reversed after optimal angioplasty in non-ARVD patients, especially young patients, suggesting reversibility of the ischemic kidney.

Experimental Renovascular Disease Induces Endothelial Cell Mitochondrial Damage and Impairs Endothelium-Dependent Relaxation of Renal Artery Segments.

BACKGROUND: Mitochondria modulate endothelial cell (EC) function, but may be damaged during renal disease. We hypothesized that the ischemic and metabolic constituents of swine renovascular disease (RVD) induce mitochondrial damage and impair the function of renal artery ECs. METHODS: Pigs were studied after 16 weeks of metabolic syndrome (MetS), renal artery stenosis (RAS), or MetS + RAS, and Lean pigs served as control (n = 6 each). Mitochondrial morphology, homeostasis, and function were measured in isolated primary stenotic-kidney artery ECs. EC functions were assessed in vitro, whereas vasoreactivity of renal artery segments was characterized in organ baths. RESULTS: Lean + RAS and MetS + RAS ECs showed increased mitochondrial area and decreased matrix density. Mitochondrial biogenesis was impaired in MetS and MetS + RAS compared with their respective controls. Mitochondrial membrane potential similarly decreased in MetS, Lean + RAS, and MetS + RAS groups, whereas production of reactive oxygen species increased in MetS vs. Lean, but further increased in both RAS groups. EC tube formation was impaired in MetS, RAS, and MetS + RAS vs. Lean, but EC proliferation and endothelial-dependent relaxation of renal artery segments were blunted in MetS vs. Lean, but further attenuated in Lean + RAS and MetS + RAS. CONCLUSIONS: MetS and RAS damage mitochondria in pig renal artery ECs, which may impair EC function. Coexisting MetS and RAS did not aggravate EC mitochondrial damage in the short time of our in vivo studies, suggesting that mitochondrial injury is associated with impaired renal artery EC function.

Correlations Between Interleukin-11 Expression and Hypertensive Kidney Injury in a Rat Model of Renovascular Hypertension.

BACKGROUND: Interleukin-11 (IL-11) is a pleiotropic cytokine of the interleukin-6 family. Recent studies revealed its crucial role in the development of cardiovascular fibrosis. In this study we examined IL-11 expression levels in the heart and the kidney exposed to high blood pressure in renovascular hypertensive rats and their correlations to fibrotic markers and kidney injury. METHODS: Two-kidney, one-clip renovascular hypertension (2K1C) was induced in rats. IL-11 expression was measured by real-time polymerase chain reaction in the left ventricle and the right kidney. The correlation of cardiac IL-11 expression with biomarkers of renal fibrosis was assessed. We further investigated IL-11 expression in 2K1C rats grouped into rats with malignant vs. nonmalignant hypertension (distinguishing criteria: weight loss, number of fibrinoid necrosis, and onion skin lesions). RESULTS: Thirty-five days after clipping, mean arterial pressure was significantly increased in 2K1C. Renal IL-11 expression was elevated in 2K1C. In the heart there was only a trend toward higher IL-11 expression in 2K1C. IL-11 in the kidney in 2K1C correlated with the expression of transforming growth factor (TGF)-ß1/2, collagens, fibronectin, osteopontin, as well as tissue inhibitors of metalloprotease 1/2. There were also correlations of IL-11 with tissue collagen expansion, number of activated fibroblasts and serum creatinine, but no correlation with mean arterial pressure. Renal expression of IL-11 was highest in rats with malignant hypertension. CONCLUSIONS: Renal IL-11 expression of renovascular hypertensive rats is markedly increased and correlates with profibrotic markers and loss of function and might therefore serve as a biomarker for the severity of hypertensive nephrosclerosis.

Aliskiren improves renal morphophysiology and inflammation in Wistar rats with 2K1C renovascular hypertension.

Hypertension is characterized by persistent elevated blood pressure levels, one of the leading causes of death in the world. Renovascular hypertension represents the most common cause of secondary hypertension, and its progress is associated with overactivation of the renin angiotensin aldosterone system (RAAS), causing systemic and local changes. Aliskiren is a renin-inhibiting drug that optimizes RAAS suppression. In this sense, the objective of the present study was to analyze the morphophysiology of the left kidney in Wistar rats with renovascular hypertension after treatment with Aliskiren. Parameters such as systolic blood pressure, urinary creatinine and protein excretion, renal cortex structure and ultrastructure, fibrosis and tissue inflammation were analyzed. Our results showed that the hypertensive animals treated with Aliskiren presented a reestablishment of blood pressure, expression of renin, and renal function, as well as a remodeling of morphological alterations through the reduction of fibrosis. The treatment regulated the laminin expression and decreased pro-inflammatory cytokines, restoring the integrity of the glomerular filtration barrier. Therefore, our findings suggest that Aliskiren has a renoprotective effect acting on the improvement of the morphology, physiology and pathology of the renal cortex of animals with renovascular hypertension.

Ligustrazine prevents basilar artery remodeling in two-kidney-two-clip renovascular hypertension rats via suppressing PI3K/Akt signaling.

OBJECTIVE: In the present study, we used a two-kidney-two-clip (2k2c) stroke-prone renovascular hypertension rat model (RHRSP) to investigate the protective effects of ligustrazine (TMP) on cerebral arteries and to examine PI3K/Akt pathway behavior under this protection. METHODS: The cerebral artery remodeling was induced by 2k2c-induced renovascular hypertension. Brain basilar artery tissues were isolated and their histological changes were detected through H&E and EVG staining, α-SMA IHC staining, and transmission electron microscopy at four, eight, and twelve weeks after 2k2c surgery, both with and without TMP treatment. Meanwhile, the ET-1, Ang II, and NO levels in basilar arteries and plasma were determined. Furthermore, the PTEN expression and the activation of PI3K/Akt in basilar artery tissues were detected through IHC and Western Blot. In addition, the primary basilar artery smooth muscle cells (BASMCs) were cultured and TMP protection of BASMCs stimulated with ET-1/Ang II in the presence or absence of insulin-like growth factor 1 (IGF-1) was determined. RESULTS: TMP attenuated basilar artery remodeling, decreased ET-1 and Ang II levels and increased NO level in basilar arteries and plasma of RHRSP rats. Moreover, TMP reduced BASMCs proliferation upon ET-1/Ang II stimulation. We also found that TMP could effectively suppress the activation of PI3K/Akt in 2k2c-RHRSP rat basilar artery and ET-1/Ang II stimulated BASMCs. Most importantly, IGF-1, as an activator of PI3K/Akt, could damage the protective effect of TMP. CONCLUSIONS: TMP exerts its protective effects and prevents basilar artery remodeling in RHRSP rats at least partly through the inhibition of PI3K/Akt pathway.

Senescent Kidney Cells in Hypertensive Patients Release Urinary Extracellular Vesicles.

Background Hypertension may be associated with renal cellular injury. Cells in distress release extracellular vesicles (EVs), and their numbers in urine may reflect renal injury. Cellular senescence, an irreversible growth arrest in response to a noxious milieu, is characterized by release of proinflammatory cytokines. We hypothesized that EVs released by senescent nephron cells can be identified in urine of patients with hypertension. Methods and Results We recruited patients with essential hypertension (EH) or renovascular hypertension and healthy volunteers (n=14 each). Renal oxygenation was assessed using magnetic resonance imaging and blood samples collected from both renal veins for cytokine-level measurements. EVs isolated from urine samples were characterized by imaging flow cytometry based on specific markers, including p16 (senescence marker), calyxin (podocytes), urate transporter 1 (proximal tubules), uromodulin (ascending limb of Henle's loop), and prominin-2 (distal tubules). Overall percentage of urinary p16+ EVs was elevated in EH and renovascular hypertension patients compared with healthy volunteers and correlated inversely with renal function and directly with renal vein cytokine levels. Urinary levels of p16+/urate transporter 1+ were elevated in all hypertensive subjects compared with healthy volunteers, whereas p16+/prominin-2+ levels were elevated only in EH versus healthy volunteers and p16+/uromodulin+ in renovascular hypertension versus EH. Conclusions Levels of p16+ EVs are elevated in urine of hypertensive patients and may reflect increased proximal tubular cellular senescence. In EH, EVs originate also from distal tubules and in renovascular hypertension from Henle's loop. Hence, urinary EVs levels may be useful to identify intrarenal sites of cellular senescence.

Hemorrhagic stroke and renovascular hypertension with Grange syndrome arising from a novel pathogenic variant in YY1AP1.

Pediatric hypertension can cause hypertensive emergencies, including hemorrhagic stroke, contributing to rare but serious childhood morbidity and mortality. Renovascular hypertension (RVH) is one of the major causes of secondary hypertension in children. Grange syndrome (MIM#602531) is a rare disease characterized by multiple stenosis or occlusion of the renal, abdominal, coronary, and cerebral arteries, which can cause phenotypes of RVH and fibromuscular dysplasia (MIM#135580). We report the case of a 7-year-old girl with Grange syndrome who showed RVH and multiple seizure episodes. At 1 year of age, she experienced seizures and sequential hemiparesis caused by a left thalamic hemorrhage without cerebral vascular anomalies. Chronic hypertension was observed, and abdominal computed tomography angiography showed characteristic bilateral renal artery stenosis. Whole-exome sequencing revealed a novel homozygous pathogenic variant in the YY1AP1 gene (NM_001198903.1: c.1169del: p.Lys390Argfs*12). Biallelic YY1AP1 mutations are known to cause Grange syndrome. Unlike previously reported patients, our patient presented with intracerebral hemorrhagic stroke without anomalous brain artery or bone fragility. The phenotype in our patient may help better understand this ultra-rare syndrome. Grange syndrome should be considered in patients presenting with childhood-onset hypertension and/or hemorrhagic stroke for early clinical intervention.

Antioxidant and antihypertensive responses to oral nitrite involves activation of the Nrf2 pathway.

Impaired redox balance contributes to the cardiovascular alterations of hypertension and activation of nuclear factor erythroid 2-related factor 2 (Nrf2) pathway may counteract these alterations. While nitrite recycles back to NO and exerts antioxidant and antihypertensive effects, the mechanisms involved in these responses are not fully understood. We hypothesized that nitrite treatment of two-kidney, one-clip (2K1C) hypertensive rats activates the Nrf2 pathway, promotes the transcription of antioxidant genes, and improves the vascular redox imbalance and dysfunction in this model. Two doses of oral nitrite were studied: 15 mg/kg and the sub-antihypertensive dose of 1 mg/kg. Nitrite 15 mg/kg (but not 1 mg/kg) decreased blood pressure and increased circulating plasma nitrite and nitrate. Both doses blunted hypertension-induced increases in mesenteric artery reactive oxygen species concentrations assessed by DHE technique and restored the impaired mesenteric artery responses to acetylcholine. While 2K1C hypertension decreased nuclear Nrf2 accumulation, both doses of nitrite increased nuclear Nrf2 accumulation and mRNA expression of Nrf2-regulated genes including superoxide dismutase-1 (SOD1), catalase (CAT), glutathione peroxidase (GPX), thioredoxin-1(TRDX-1) and -2 (TRDX-2). To further confirm nitrite-mediated antioxidant effects, we measured vascular SOD and GPX activity and we found that nitrite at 1 or 15 mg/kg increased the activity of both enzymes (P < 0.05). These results suggest that activation of the Nrf2 pathway promotes antioxidant effects of nitrite, which may improve the vascular dysfunction in hypertension, even when nitrite is given at a sub-antihypertensive dose. These findings may have many clinical implications, particularly in the therapy of hypertension and other cardiovascular diseases.

Naringenin Ameliorates Renovascular Hypertensive Renal Damage by Normalizing the Balance of Renin-Angiotensin System Components in Rats.

Background: Naringenin, a member of the dihydroflavone family, has been shown to have a protective function in multiple diseases. We previously demonstrated that naringenin played a protective role in hypertensive myocardial hypertrophy by decreasing angiotensin-converting enzyme (ACE) expression. The kidney is a primary target organ of hypertension. The present study tested the effect of naringenin on renovascular hypertensive kidney damage and explored the underlying mechanism. Methods and Results: An animal model of renovascular hypertension was established by performing 2-kidney, 1-clip (2K1C) surgery in Sprague Dawley rats. Naringenin (200 mg/kg/day) or vehicle was administered for 10 weeks. Blood pressure and urinary protein were continuously monitored. Plasma parameters, renal pathology and gene expression of nonclipped kidneys were evaluated by enzyme-linked immunosorbent assay, histology, immunohistochemistry, real-time polymerase chain reaction, and Western blot at the end of the study. Rats that underwent 2K1C surgery exhibited marked elevations of blood pressure and plasma Ang II levels and renal damage, including mesangial expansion, interstitial fibrosis, and arteriolar thickening in the nonclipped kidneys. Naringenin significantly ameliorated hypertensive nephropathy and retarded the rise of Ang II levels in peripheral blood but had no effect on blood pressure. 2K1C rats exhibited increases in the ACE/ACE2 protein ratio and AT1R/AT2R protein ratio in the nonclipped kidney compared with sham rats, and these increases were significantly suppressed by naringenin treatment. Conclusions: Naringenin attenuated renal damage in a rat model of renovascular hypertension by normalizing the imbalance of renin-angiotensin system activation. Our results suggest a potential treatment strategy for hypertensive nephropathy.

A novel method for comparison of arterial remodeling in hypertension: Quantification of arterial trees and recognition of remodeling patterns on histological sections.

Remodeling of spatially heterogeneous arterial trees is routinely quantified on tissue sections by averaging linear dimensions, with lack of comparison between different organs and models. The impact of experimental models or hypertension treatment modalities on organ-specific vascular remodeling remains undefined. A wide variety of arterial remodeling types has been demonstrated for hypertensive models, which include differences across organs. The purpose of this study was to reassess methods for measurement of arterial remodeling and to establish a morphometric algorithm for standard and comparable quantification of vascular remodeling in hypertension in different vascular beds. We performed a novel and comprehensive morphometric analysis of terminal arteries in the brain, heart, lung, liver, kidney, spleen, stomach, intestine, skin, skeletal muscle, and adrenal glands of control and Goldblatt hypertensive rats on routinely processed tissue sections. Mean dimensions were highly variable but grouping them into sequential 5 µm intervals permitted creation of reliable linear regression equations and complex profiles. Averaged arterial dimensions demonstrated seven remodeling patterns that were distinct from conventional inward-outward and hypertrophic-eutrophic definitions. Numerical modeling predicted at least nineteen variants of arterial spatial conformations. Recognition of remodeling variants was not possible using averaged dimensions, their ratios, or the remodeling and growth indices. To distinguish remodeling patterns, a three-dimensional modeling was established and tested. The proposed algorithm permits quantitative analysis of arterial remodeling in different organs and may be applicable for comparative studies between animal hypertensive models and human hypertension. Arterial wall tapering is the most important factor to consider in arterial morphometry, while perfusion fixation with vessel relaxation is not necessary. Terminal arteries in organs undergo the same remodeling pattern in Goldblatt rats, except for organs with hemodynamics affected by the arterial clip. The existing remodeling nomenclature should be replaced by a numerical classification applicable to any type of arterial remodeling.

Long non-coding RNA cytoskeleton regulator RNA (CYTOR) modulates pathological cardiac hypertrophy through miR-155-mediated IKKi signaling.

Pathological cardiac hypertrophy, which may lead to heart failure and sudden death, can be affected by multiple factors. In our previous study, we revealed that IKKi deficiency induced cardiac hypertrophy through the activation of the AKT and NF-kB signaling pathway in response to aortic banding (AB). Non-coding RNAs, mainly long non-coding RNAs (lncRNAs) and microRNAs (miRNAs), play a crucial role in normal developmental and pathological processes. In the present study, microarray analysis results from GEO database were analyzed, and upregulated lncRNAs in cardiac hypertrophy were identified. Of them, lncRNA cytoskeleton regulator RNA (CYTOR) obtained a fold-change of 6.16 and was positively correlated with IKBKE according to the data from The GTEx project. CYTOR knockdown significantly enhanced the inducible effect of AB operation on mice myocardial hypertrophy and Angiotensin II on cardiomyocyte hypertrophy. Moreover, miR-155 was significantly related to hypertrophic cardiomyopathy (HCM, |hsa05410) and predicted to target both CYTOR and IKBKE. Luciferase reporter and RIP assays revealed that CYTOR served as a ceRNA for miR-155 to counteract miR-155-mediated repression of IKBKE. Moreover, CYTOR knockdown reduced IKKi protein levels while activated NF-kB signaling pathway, whereas miR-155 inhibition exerted an opposing effect; the effect of CYTOR could be partially attenuated by miR-155 inhibition. Taken together, CYTOR might play a protective role in cardiac hypertrophy through miR-155 and downstream IKKi and NF-κB signaling, most possibly through serving as a ceRNA for miR-155 to counteract miR-155-mediated repression of IKBKE.

Bone marrow mononuclear cell transplantation rescues the glomerular filtration barrier and epithelial cellular junctions in a renovascular hypertension model.

NEW FINDINGS: What is the central question of this study? Can a single bone marrow mononuclear cell (BMMC) transplant into the subcapsular region of kidney improve cellular communication and adhesion, while restoring renal tissue cytoarchitecture and function during renovascular hypertension? What is the main finding and its importance? The BMMC transplantation restored connexin 40 expression and led to recovery of N- and E-cadherin levels within 15 days. It was observed, for the first time, that BMMC transplantation restores expression of nephrin, a component of the glomerular filtration barrier related to podocytes and the glomerular basal membrane. ABSTRACT: Stem cell therapy has emerged as a potential treatment for renal diseases owing to the regenerative potential of stem cells. However, a better understanding of the morphological and functional changes of damaged renal cells in the presence of transplanted stem cells is needed. The aim of this study was to investigate cell-cell communication and adhesion in renal parenchyma, with analysis of fibrosis, to evaluate renal morphology and function after bone marrow mononuclear cell (BMMC) transplantation in two-kidney-one-clip rats. The BMMC therapy significantly decreased blood pressure and renin expression, improved renal morphology and restored the glomerular filtration barrier, with remodelling of podocytes. In addition, there was a reduction in fibrosis, and connexin 40 and nephrin expression were significantly increased after 7 and 15 days of transplantation. Plasma creatinine, urea and total protein levels were restored, and proteinuria was reduced. Furthermore, N- and E-cadherin expression was increased soon after BMMC therapy. Green fluorescent protein-positive BMMCs were found in the renal cortex 24 and 48 h after transplantation into the renal subcapsule, and at 7 and 15 days after transplantation, these cells were observed throughout the renal medulla, indicating cellular migration. Therefore, these data suggest that transplanted BMMCs improve cell-cell communication and adhesion between damaged cells, which is accompanied by a recovery of renal morphology and function.

Importance of the commissural nucleus of the solitary tract in renovascular hypertension.

The rodent renovascular hypertension model has been used to investigate the mechanisms promoting hypertension. The importance of the carotid body for renovascular hypertension has been demonstrated. As the commissural NTS (cNTS) is the first synaptic site in the central nervous system that receives information from carotid body chemoreceptors, we evaluated the contribution of cNTS to renovascular hypertension in the present study. Normotensive male Holtzman rats were implanted with a silver clip around the left renal artery to induce two-kidney, one-clip (2K1C) hypertension. Six weeks later, isoguvacine (a GABAA agonist) or losartan (an AT1 antagonist) was injected into the cNTS, and the effects were compared with carotid body removal. Immunohistochemistry for Iba-1 and GFAP to label microglia and astrocytes, respectively, and RT-PCR for components of the renin-angiotensin system and cytokines in the NTS were also performed 6 weeks after renal surgery. The inhibition of cNTS with isoguvacine or the blockade of AT1 receptors with losartan in the cNTS decreased the blood pressure and heart rate of 2K1C rats even more than carotid body removal did. The mRNA expression of NOX2, TNF-α and IL-6, microglia, and astrocytes also increased in the cNTS of 2K1C rats compared to that of normotensive rats. These results indicate that tonically active neurons within the cNTS are essential for the maintenance of hypertension in 2K1C rats. In addition to signals from the carotid body, the present results suggest that angiotensin II directly activates the cNTS and may also induce microgliosis and astrogliosis within the NTS, which, in turn, cause oxidative stress and neuroinflammation.

Matrix metalloproteinase (MMP)-2 activation by oxidative stress decreases aortic calponin-1 levels during hypertrophic remodeling in early hypertension.

Hypertension is characterized by maladaptive vascular remodeling and enhanced oxidative stress in the vascular wall. Peroxynitrite may directly activate latent matrix metalloproteinase (MMP)-2 in vascular smooth muscle cells (VSMC) by its S-glutathiolation. MMP-2 may then proteolyze calponin-1 in aortas from hypertensive animals, which stimulates VSMC proliferation and medial hypertrophy. Calponin-1 is an intracellular protein which helps to maintain VSMC in their differentiated (contractile) phenotype. The present study therefore investigated whether aortic MMP-2 activity is increased by oxidative stress in early hypertension and then contributes to hypertrophic arterial remodeling by reducing the levels of calponin-1. Male Wistar rats were submitted to the two kidney, one clip (2 K-1C) model of hypertension or sham surgery and were treated daily with tempol (18 mg/kg/day) or its vehicle (water) by gavage from the third to seventh day post-surgery. Systolic blood pressure (SBP) was daily assessed by tail-cuff plethysmography. After one week, aortas were removed to perform morphological analysis with hematoxylin and eosin staining and to analyze reactive oxygen­nitrogen species levels by dihydroethidium and immunohistochemistry for nitrotyrosine. MMP-2 activity was analyzed by in situ and gelatin zymography and its S-glutathiolation was analyzed by Western blot for MMP-2 of anti-glutathione immunoprecipitates. Calponin-1 levels were identified in aortas by immunofluorescence. SBP increased by approximately 50 mmHg at the first week in 2 K-1C rats which was unaffected by tempol. However, tempol ameliorated the hypertension-induced increase in arterial media-to-lumen ratio and hypertrophic remodeling. Tempol also decreased hypertension-induced aortic oxidative stress and the enhanced MMP-2 activity. S-glutathiolation may be a potential mechanism by which oxidative stress activates MMP-2 in aortas of 2 K-1C rats. Furthermore, calponin-1 was decreased in aortas from 2 K-1C rats and tempol prevented this. In conclusion, oxidative stress may contribute to the increase in aortic MMP-2 activity, possibly by S-glutathiolation, and this may result in calponin-1 loss and maladaptive vascular remodeling in early hypertension.

Nitrite treatment downregulates vascular MMP-2 activity and inhibits vascular remodeling in hypertension independently of its antihypertensive effects.

Hypertension is associated with cardiovascular remodeling. Given that impaired redox state activates matrix metalloproteinase (MMP)- 2 and promotes vascular remodeling, we hypothesized that nitrite treatment at a non-antihypertensive dose exerts antioxidant effects and attenuates both MMP-2 activation and vascular remodeling of hypertension. We examined the effects of oral sodium nitrite at antihypertensive (15 mg/kg) or non-antihypertensive (1 mg/kg) daily dose in hypertensive rats (two kidney, one clip; 2K1C model). Sham-operated and 2K1C hypertensive rats received vehicle or nitrite by gavage for four weeks. Systolic blood pressure decreased only in hypertensive rats treated with nitrite 15 mg/Kg/day. Both low and high nitrite doses decreased 2K1C-induced vascular remodeling assessed by measuring aortic cross-sectional area, media/lumen ratio, and number of vascular smooth muscle cells/aortic length. Both low and high nitrite doses decreased 2K1C-induced vascular oxidative stress assessed in situ with the fluorescent dye DHE and with the lucigenin chemiluminescence assay. Vascular MMP-2 expression and activity were assessed by gel zymography, Western blot, and in situ zymography increased with hypertension. While MMP-2 levels did not change in response to both doses of nitrite, both doses completely prevented hypertension-induced increases in vascular MMP activity. Moreover, incubation of aortas from hypertensive rats with nitrite at 1-20 µmol/L reduced gelatinolytic activity by 20-30%. This effect was fully inhibited by the xanthine oxidase (XOR) inhibitor febuxostat, suggesting XOR-mediated generation of nitric oxide (NO) from nitrite as a mechanism explaining the responses to nitrite. In vitro incubation of aortic extracts with nitrite 20 µmol/L did not affect MMP-2 activity. These results show that nitrite reverses the vascular structural alterations of hypertension, independently of anti-hypertensive effects. This response is mediated, at least in part, by XOR and is attributable to antioxidant effects of nitrite blunting vascular MMP-2 activation. Our findings suggest nitrite therapy to reverse structural alterations of hypertension.